I'm toying with an idea and am curious to know what type of hp/tq can be expected from a 18:1 build with an intercooler that would provide longevity and reliability? I know there's likely lots of flavours to consider other than the compression and an intercooler such as injectors a different injection pump and turbo but I am not that familiar with the 6.5 other than the usual "unreliable, stay away from GM diesels" that I hear so I didn't want to muddy the water. I know all of the naysayers are piling it on a little thick so I'm putting the question to the users.

Thanks!!:cool:

We are just a few humble folks who are too cheap to buy the Durabucks Diesel that GM now offers. :)

6.5 is a pretty fair design. Hummer is using it now. The military is using it. So it ain't all junk as the big spenders would like you to believe.

18:1 is the dream setup for the 6.5. May take a bit more to start it in the dead of winter . . .

Stanadyne is the only IP available to my knowledge for the 6.5. Are you building a tow vehicle, a dragster, or grocery getter?

Stock, read as 195hp (I forget the torque). 18:1 you'll get more boost and less stress on the engine. Now, you'll just have to figure out how to get more fuel in there if that's what you're after.

I am running an 18:1 6.5. I just got it, the engine that is, about a week ago. I shelled out a lot for it, about 6 g's for the short block. So far, I am pleased though. It runs very well and seems to put out gobbs of power. I am boosting the max out of the GM8 turbo, right around 20 psi while I could use about 5 more psi.

So far though, I have only put about 1200 miles. I am putting a trailer behind it this weekend to see how she pulls now that it is broken in. I am putting an intercooler on it in a few days too so I will keep everything posted that happens.

As far as the GM "Red Headed Step Child" Engine goes, the old blocks really do not hold up, mainly the 97-00 506 with the oil spray piston cooling. The block that I have is a 2005 revised casting with a bunch-o-changes.

Well since I've already forked over for the Durabucks - I guess that would be still forking over, I don't really want to drop another 1/2 a house to upgrade our minivan in a couple of years. I was hoping to find a late model 2500 suburban with a 6.5L and when I'm done hopefully have a 0 mile vehicle to start with that didn't cost me 60 Grand or whatever they're going to be. I suppose I could start with any Suburban and transplant the 6.5L but it would be easier to start with one that had one. On the other hand I don't want to get involved with a money pit either with respect to O & M costs after the fact either.

I'm toying with an idea and am curious to know what type of hp/tq can be expected from a 18:1 build with an intercooler that would provide longevity and reliability? I know there's likely lots of flavours to consider other than the compression and an intercooler such as injectors a different injection pump and turbo but I am not that familiar with the 6.5 other than the usual "unreliable, stay away from GM diesels" that I hear so I didn't want to muddy the water. I know all of the naysayers are piling it on a little thick so I'm putting the question to the users.

Thanks!!:cool:

If you go with a Penisular HO Turbo and Fuel Pump you can get 300 BHP out of them, they also build a dual Turbo Unit that puts oput 400 HP but I think tha woud reduce life a bunch. I know a guy that Has about 170,000 miles on his 300HP 18-1 6.5. I have 192,000 on my modest modified 6.5 with no major problems. (IMNSHO). There are folks that have gotten 400,000 miles out of stock 6.5's with no major problems.

What kind of torque would be on tap for a 300 hp 6.5?

Suggest you visit Peninsulars site, they have pushed the 6.5 near about as far as anybody has tried

I have passed the break in miles of my Peninsular 18:1 engine. Went to Rock Island, IL and towed a 3500 - 4000 lb (guesstimate) barge/tritoon boat about 400 miles (200 one way) over the weekend. The truck pulls like I expected. The sweet spot appears to be at about the 2000 rpm range and 6 psi of boost. Changed oil to 15W40 Amsoil synthetic before trip. I am running a stock IP and turbo.

Here is an update:

Towing boat at 65 mph, about 90 degrees outside.
Coolant temp never went over 190
Oil temp (before cooler) never went over 250
Boost was about 7 psi plus or minus depending on road, etc. Went up to 14 once while getting on highway ramp (it really wanted to go! but I let off when I saw the boost gauge). Kept it under 10 climbing hills, and passing.
EGT never went over 800 and mostly stayed at about 500 - 600. (preturbo temp)
Fuel mileage was just a tick under 15 mpg

Unloaded at 65mph
Coolant temp never exceeds 190, mostly hangs under 180.
Oil temp, (before cooler)ranges 220 - 240
Boost stays about 4 psi plus or minus
EGT usually about 300 - 500
Fuel mileage just over 18 mpg. (measured on first tankful, which included prebrake-in miles and some idling while fixing AC)

HH65:
Did you get a long block? What made you want to get the 18:1? I am curious;) . And hey, you do not live too far from me. Same State at least.

Also, why are you leaving the boost so low? I am cranking 20 psi right now and gonna hit 25 but with a different turbo. These 18:1 are about boost and using the turbo to do the grunt work. Let me know how things work out with your Pen engine, I just tripped 1000 miles on mine.

You are getting some good milage so far. Sounds like you are keeping your foot off the floor.

C TDP

I went with the Peninsular 18:1 long block for a couple reasons. Main one, I felt it would last longer, Peninsular has a good reputation and history, additionally I could always add a larger turbo and a high performance IP later. Also the engine is not as noisy at speed.

I bought the long block because for the price difference, it was about the same to have the heads reconditioned and purchase the bolts, my time to assemble, etc, ... simpler in the long run and can sell or save heads and other parts for future projects.

The towing mileage is better than the previous engine, probably because the 18:1 with the turbo master is buring more efficiently. Unloaded mileage is about the same as old engine.

The boost is set at a starting point. I plan to turn up slightly. With my stock IP, it is my understanding that about 8 psi at 65mph while towing will be a good place to be at.

I am at about 1800 miles now. Last tankful was a 10% bio diesel fuel from IL. I hear that is now required in IL? Is that true?

Since when did SE WI become part of IL, ......Hmmmm.....oh I forgot, Kenosha, WI is now a NW suburb of Chicago. :rolleyes: I am actually in Burlington, about 20 minutes from the stateline and Kenosha. I had some friends who used to work and live in Crystal Lake.

What is my number in the low pressure club?

I will post future updates on my engine. Hope to see yours also!